[CMake] Add Android toolchain CMake cache files.

Summary: Thoes files are used to build Android toolchain. D32816 makes it possible to build runtimes for targets.

Reviewers: beanz, srhines

Reviewed By: srhines

Subscribers: pirama, jroelofs, srhines, cfe-commits, mgorny

Differential Revision: https://reviews.llvm.org/D33561

llvm-svn: 309407